Concentration of ores and the like



UNITED STATES PATENT OFFICE.

ALFRED SGHWARZ, OF J'OPLIN, MISSOURI, ASSIGNOR TO METALS RECOVERY COMPANY,

OF NEW YORK, N. Y., A CORPORATION OF MAINE.

CONCENTRATION OF ORES AND THE LIKE.

No Drawing. Application filed March 6, 1917, Serial No. 152,585. Renewed May 6, 1921.

Specification of Letters Patent.

Patented Oct. 25, 1921.

Serial No.

T 0 all whom it may concern:

Be it known that I, ALFRED SoHwARz, a subject of the Emperor of Germany, re siding in Joplin, county of Jasper, State of Missouri, have invented certain new and useful Improvements in the Concentration of Ores and the like; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to the concentration of ores and the separation of the metallic constituents from the gangue.

Heretofore, various methods of concentrating ores have been proposed depending upon the coagulation of the mineral particles or the formation of froth therefrom by the addition of selective agent substances, such as oils, oily substances, and the like. Such processes may be roughly divided into those which make use of such selective agent substances and the like, and those which depend upon gas development on the mineral particles by chemically attacking the mineral. Processes in which selective agent substances and the like are used may again be divided roughly into coagulation processes, where the coagulated mineral is extracted from the gangue by difierential sedimentation, or by other suitable methods; the bulk flotation process by which oils and the like in comparatively large quantities envelop the mineral particles and float themoif, the quantity of oil being sufiicient to give buoy ancy to a given amount of mineral present; and froth flotation processes in which small quantities of selective agent substances and the like are used and the necessary buoyancy obtained by the addition of air or gas.

The methods heretofore proposed based upon the use of Selective agents for effecting concentration by flotation have utilized, as such materials, the various oil distillates and by-products which are available commercially in suflicient quantities and at a sufficiently low cost.

I have determined, as the result of careful experimentation, that the selective action of the common selective agent substances (oils mon flotation agents which are commonly considered soluble nevertheless contain considerable amounts of insoluble constituents so that these agents differ from the so-called insoluble and immiscible oils only in deree.

When such insoluble oils or so-called soluble agents (containing accompanying insoluble constituents) are used for flotation and ore concentration purposes, it is customary and usually essential for them to be intimately incorporated with the ore pulp by agitation or otherwise. Such oils contain the soluble constituents intimately combined with and distributed throughout the insoluble oil; and similarly the so-called soluble agents contain their insoluble constituents intimately distributed throughout their mass. The effect of these insoluble constituents is to mask and. bind the soluble constituents so that the soluble constituents are not readily disclosed and rendered available. Nevertheless it seems to be essential that such soluble substances be incorporated with the ore pulp to a suflicient extent to render the same active, to a greater or less extent, in order for effective flotation to take place.

When insoluble oil constituents are present, as with the common oils used commercially for flotation purposes, the amount of the insoluble constituents is often so great,

compared with the soluble constituents, that V the concentrating operation is materially retarded. With certain ores, particularly ores with notable amounts of colloidal gangue, theinsoluble oil tends to combine with the colloidal gangue so that there is obtained a dirty concentrate. 'In fact, the results obhined in many cases indicate that the ining to which the disadvantages of prior procsoluble oil constituents have a preferential affinity for gangue and tend to float the gangue rather than, or along with, the mineral constituents. Where, however, colloidal gangue is not present in any appreciable amount, and particularly where the ore 18 not finely ground, a certain amount of insoluble oily matter seems necessary for the best results in flotation practice.

The present invention relates to a concentration method of treating ores and of separating the minerals from the gangue accordesses are largely overcome or minimized.

Instead of using common flotation substances (oils and oily substances) containing varying and undetermined amounts of soluble and insoluble constituents, with the soluble constituents so intimately combinedwith the insoluble'that their action .is retarded, the present invention comprises a process according to which the selective agent substances are first subjected to an extraction process to extract the soluble from the insoluble or difiicultly soluble constituents, which are then separated from each other, and the soluble constituents are then used with predetermined amounts of the insoluble constituents where the presence of such insoluble constituents in predetermined proportions is desirable in the oreconcentrating operation.

Ores to be concentrated vary greatly in their nature and in the physical and chemical characteristics of their constituents, both as to gangue and as to mineral constituents. It is a matter of common knowledge that different types of ore require different treatments for their concentration and that a treatment which will give satisfactory results with one ore will give uite unsatisfactory results with another. ven the water available for milling purposes may, and often does, influence the treatment of the mineral and the method of concentration.

I have found'that the concentration of ores by the action of selective agents, and particularly the concentration of ores by flotation, can be materially promoted by subjecting selective agent substances, such 'as those commonly used in flotation (in using the generic term selective agent substance I include oil, resins, tars, etc.) to an extraction operation in order to separate the soluble constituents thereof from the insoluble or diflicultly soluble constituents, and by then carrying on the concentrating operation with the soluble constituents thus extracted, such soluble constituents being combined with predetermined amounts ofseparated insolubleconstituents, depending upon the particular ore to be treated.

I have found that the common selective agent substances used for flotation purposes .(and I believe all such substances) can be separated, by a proper extraction process, into soluble and insoluble constituents, thi's being true as well of the so called insoluble and immiscible oils used for many years in flotation processes as of the so-called soluble flotation agents which nevertheless may contain notable amounts of insoluble constituents, the difl'erence between these common socalled soluble and insoluble flotation agents of an oily nature being largely, if not entirely, one of degree.

I have also found that whensuch selective agent substances (including not only such oils andoily substances, but also substances solid at normal temperatures), are subjected to an extraction operation, and the resulting soluble constituents thereof used for flotation purposes, with the addition thereto in predetermined amounts of the insoluble constituents, a materially cleaner separation and concentrate can be obtained than has been heretofore commonly obtained in flotation processes. I believe this to be due largely, if not entirely, to the reduction of such insoluble constituents to the necessary extent, so that these insoluble constituents do not exert their selective action upon the gangue constituents and float such gan e constituents with the mineral particles. ecause of the widely varying nature of ores, it will be evident that the relative amount of the insoluble constituents will require to be determined for the particular ore under consideration. According to the present invention, it is possible to use such predetermined amounts; whereas, with prior procedures with which I am familiar, this has not been possible, inasmuch as it has been the common practice to add all of the oil or other selective agent substance, with unsoluble constituentsas they naturally occur indiscriminately distributed and held by each other, require to be thoroughly disseminated throughout the ore pulp, an excessive amount of power usually being necessary to liberate the soluble portions and make them active. This often results, as has been pointed out, in the selective separation also with the mineral particles of more or less of the gangue constituents.

The method of extracting from the crude selective agent substances, agents or substances to be used for the concentration of ores, may be practised in various ways. These selective agent substances, for example pine tar or pine oil, resin or resin oil, or various coal tar fractions, and the like,

may be agitated either in hot or cold wateror may be boiled with water, with agitation, if necessary, in order to extract the soluble from the relatively insoluble constituents. The extraction may be in some cases promoted by the addition of various re-agents such as dilute alkalis, the active concentrating constituents being subsequently again separated into insoluble and soluble constituents by the addition of acids, metallic salts, or the like, where acid-insoluble constituents, etc., are extracted. The raw materials which may thus be extracted, may be, as above indicated, such common and cheap oils and oily substances as are commonly used for flotation purposes, 6; g., resin, pine oil, etc. Certain crude materials or raw products which themselves are the sources of oils (as by destructive distillation) may themselves serve as sources of selective agent material to be extracted. Such substances will necessarily varyboth in the nature .and the amount of the soluble constituents extracted. I have found that resin is of particular value as a source of extractive constituents. Pine tar and pine oil are also of considerable value as is also creosote. Crude petroleum oil is of relatively less value in that a much larger amount of it is required for producing, an equivalent amount of extractive constituents. The se aration or extraction of the soluble constituents from selective agent substances may sometimes leave an insoluble product of enhanced value for the other purposes for which such products are commonly used. That is to say, the removal or extraction of readily soluble constituents is often an advantage in that the resulting insoluble oils or solids are of higher purity and consequently greater value.

When predetermined amounts of the insoluble or difficultly soluble constituents are recombined with the soluble extracted constituents, the soluble portions or constituents appear to establish, a bond between the mineral and the insoluble constituents so that the coagulation or flotation of the particles constituents.

is promoted by the presence of the insoluble constituents. It is thus possible, by regulating the relative amounts and proportions of soluble and insoluble constituents, to regulate the consistency of the coagula or of the froth, and to secure a more perfect separation of the mineral, and at the same time to avoid any objectionable excess of insoluble here 'certain materials, for example resin, are subjected to an extraction operation, there may be obtained soluble constituents which are capable of being precipitated or separated in a flocculent form which is of particular value for the treatment of certain ores when used in combination with the remaining soluble constituents. If thus.

resin is dissolved in an alkali and re-precipitated with an acid r a mineral salt such as lime, the insoluble portions will be in the form of a flocculent precipitate, (provided that the solution is not sufiiciently hot to cause the precipitate to melt and recombine), which flocculent precipitate is readily distributed or disseminated through the ore pulp. This precipitate can be separated from the soluble constituents and recombined therewith in predetermined amount in the manner above pointed out.

Again, where the extracted portions of certain materials contain constituents which are objectionable in the ore concentration operation, these constituents may be removed by purification of the extract or by precipitation or otherwise.

Instead of effecting the extraction and separation of the selective agent substances before the addition of the separated constituents to the ore pulp, this extraction and separation may be effected in the ore pulp itself, a small amount of the pulp being sufficient for this purpose. The insoluble constituents can then be separated and recombined, in predetermined amounts. In certain cases it may even be advantageous to combine the extraction with a concentration operation in such a way that any large excess of insoluble constituents is removed with certain ore constituents during a preliminary concentration. and the soluble constituents, present in solution in large excess, utilized for a further concentration by adding to new amounts of ore pulp. Since the insoluble constituents are valuable in connection with the coarser fractions of ore, such coarser fractions can be concentrated to advantage with the entire amount of insolu ble constituents present, and the solution of soluble constituents, remaining after the preliminary concentration and extraction, utilized in the subsequent concentration of the finer fractions containing larger amounts of fine gangue.

I will describe'the invention more in detail in connection with certain embodiments thereof, but in view of the complicated nature of the art, it will be understood that the invention is il ustrated by, but is not limited to, these specific illustrations.

As an example, resin may be subjected to the action of a 1% solution of sodium hydroxid until as much as possible of the resin has been taken into solution. he mass may then, if desired, be treated with a suitable acid in sufiicient quantities to neutralize all or part of the alkali or even such amount that there will be an excess of acid present. The precipitate formed may be separated from the dissolved constituents and if desired recombined therewith in predetermined proportions.

The following more detailed description will illustrate one specific embodiment of the invention as applied to the treatment of a zinc ore of the Joplin district: 40 parts by weight of common resin are dissolved in 2000 parts of water containing 40 parts of caustic soda dissolved therein, and the mixture is heated to boiling. 40 parts of litharge or its equivalent in lead acetate are added afterthe resin is in solution and the mixture is maintained hot for about two hours. Thereafter, the solution is filtered, preferably hot, and any desired amount of it is then subjected to treatment with sulfuric acid. 30 parts by weight of the mixture may be taken for 500 parts by weight of the ore, although greater or lesser proportions are effective. The 30 parts of liquor are acidified with about 3 parts of a 10% sulfuric acid solution which causes the precipitation of resin previously in solution. The precipitate is filtered ofi and the filtrate together with predetermined amounts of the precipitate is then added to the 500 parts of ore, the ore having been previously ground to pass an mesh screen. The ore is placed in a flotation machine such as those of the common types, and 3000 parts of water added. The solution containing the soluble extracted constituents together with the precipitate is added and the mass agitated about 3 minutes to distribute the same throughout the ore pulp. The resulting mass is then subjected to a flotation treatment for the production of a froth which is removed in any suitable manner. From an ore containing zinc in the form of zinc blende about 5.8%, lead approximately 2%, and iron about 1.5%. and with a gangue consisting principally of silica known as Joplin flint rock, I have obtained a concentrate containing 56% zinc, approximately 10% lead, 1.4% iron, and 1.5% insolubles. The tailings contained about 0.8% zinc, and a small fraction of lead, the remainder being the .flint rock carrying the residual iron. I Again, I have separated pyritic iron from a gangue containing a small amount of lime, by using the solution referred to which was allowed to remain slightly alkaline and by adding thereto about one-half of the preclpitate resulting from the acid treatment of the alkaline solution of the resin. In this way I have obtained an excellent extrac tion of the pyritic iron from the gangue.

As other instances of the application of the invention, there may be used for the flotation of ores the solution obtained by boiling resin'with water and by separation of the undissolved resin from the water together with predetermined amounts of the undissolved' resin constituents. So, also, there may be used the solution obtained by subjecting a suitable oil, such as pine 011, to violent agitation with cold or hot water, and by then filtering off the insoluble oily residue. In place of resin, tar or certain other oils containing-constituents soluble in alkalis may be dissolved in an alkali and part of the dissolved constituents precipitated with an acid, the precipitate being filtered off and the: resulting filtrate used for the concentration of minerals. In addition to such solutions there may be added any predetermined proportion of the precipitate or of the inso uble residue in order to intensify the froth or coagula in accordance with the requirements of the mechanical eparation of the collected mineral from the gangue. In some cases, even a slightly alkaline solution may be added to the ore pulp without first completelyprecipitating the constituents insoluble in acids. also, precipitation may be effected with a metal or an alkali salt instead of with an acid. Again, a combination of various solutions with each other, or of different solutions with different insoluble or precipitated constituents in predetermined proportions may be used.

- Instead of first extracting the resin and separating it into its constituents, this may be eflected in admixture with the ore pulp by agitating the resin with a small amount of the ore pulp made alkaline, then acidifying and skimming off or otherwise removing the insoluble constituents, and adding the acidified pulp containing the soluble constituents dissolved'therein, to the bulk of the ore to be concentrated, the concentration being then effected.

The extraction of the readily soluble contituents by the ore pulp can generally be effected by the various methods of extraction already referred to, for example, by agitation with the pulp alone, or with added acid or alkali, or by heating, etc.

It will accordingly be seen that the invention is not limited to the use of the soluble or the insoluble rtions' of the selective agent substances oil or other mineral collecting medium) nor does it involve the use of these constituents in the accidental proportions in which they naturally occur; but 1t involves a se aration of the readily soluble from the dlfiicultly soluble or insoluble, constituents, and the utilization of the soluble constituents and insoluble constituents in predetermined proportions, in accordance with the requirements of the particular ore to be concentrated. ..-.It is thus possible to regulate the nature and quality of the substance added for effecting the concentration of the-mineral particles so that a more firfect separation can beobtained and one tter adapted for regulation in accordance with different ores to be treated. At the same time, there is avoided, as above pointed. out, the indiscriminate addition of inrelatively I soluble constituents in large excess such as they often occur in the usual flotation agents.

Moreover, while with 'common flotation agents the soluble constituents are surrounded by insoluble or diflicultly soluble constituents, oil, rease, resins and the like, so that they can go in solution only with difliculty, the present invention enables the soluble constituents to be utilized to advantage without the objections incident to the prior practice. Moreover, the excess of insoluble constituents i removed and made available for other purposes while, at the same time, improving the value of thevextracted portion of the composition or substances obtained by the extraction process. While. excessive amounts of insoluble constituents might again absorb the extracted constituents and thus interfere with their free action,the separation of these constituents and the utilization of the separated constituents, or even the utilization of these constituents when combined in predetermined proportions, enable such disadvantages to be overcome because of the avoidance of excessive amounts of either the soluble or the insoluble constituents.

It will be noted that the invention involves a. process which is not only a marked improvement in the flotationconcentration, and in other concentration processes using selective agents; but that it is also one of notatable economy in that improved results are obtained by the use of inexpensive materials which are "treated by an inexpensive procedure to give agents or substances used in the concentration of ores to particular advantage.

In referring to the concentration of ores, I intend toinclude the treatment of various minerals both in run-of-Inine ores and other minerals'as well as concentrates, slimes or other ore or mineral concentrates or residues which may have been subjected to preliminary separation or concentration treatments or which may have resulted from such preliminary treatments.

I claim:

1. The method of concentrating ores by the action of selective agents and by flotation which comprises disintegrating by extraction selective agent substances containing soluble and insoluble constituents, separating such soluble constituents from the insoluble constituents, adding predetermined proportions, diflering from the original of such soluble constituents and the insoluble constituents to the ore to be concentrated,-

and then subjecting the ore'to a flotation operation; substantially as described.

2. The method of concentrating ores by the action of selective agents and by flotation which comprises disintegrating by extraction selective agent substances containing soluble and insoluble constituents, separating the solution of such soluble constituents from the insoluble constituents, adding predetermined proportions, differing from the original of the solution of such soluble constituents and the insoluble constituents to the ore to be concentrated, and then subjecting the ore to a flotation operation; substantially as described.

3, The method of concentrating ores by the action of selective agents which comprises adding to the ores to be concentrated, soluble constituents extracted and separated from the insoluble constituents of selective agent substances together with predetermined proportions, differing from the original of the insoluble constituents, and subjecting the ore to a flotation operation; substantially as described.

4. The method of concentrating .ore's by the action of selective agents which comprises adding to part of the ore pulp selective agent substances containing soluble and insoluble constituents, extracting the soluble from the insoluble constituents within the pulp, separating the insoluble constituents, addlng the ore pulp with soluble constituents to the main body of ore pulp, and subjecting the sameto a flotation operation, the amount of selective agents added with the part of the ore pulp being sufficient for the flotation of the larger body of the ore pulp; substantially as described.

5. The method of concentrating ores by the action of selective agents which comprises adding to part of the ore pulps a large excess of selective agent substances containing soluble and insoluble constituents, extracting the soluble from the insoluble constituents and removing the insoluble constituents from the pulp, combining the resulting pulp with the main portion of the pulp and subjecting the same to a concentrating operation; substantially as described.

6. The method of concentrating ores by the action of selective awnts which comprises adding to part of the ore pulp selective agent substances containing soluble and insoluble constituents, extracting the soluble from the insoluble constituents and removing the insoluble constituents from the pulp, combining the resulting pulp, together with. predetermined amounts of the separated insoluble constituents with the main portion of the pulp and subjecting the same to a concentrating operation substantially as described.

7. The method of concentrating ores by the 'action .of selective agents which comprises subjecting a resin to extraction with an alkali, precipitating insoluble constituents, byth' addition of an acid, adding the remaining soluble extract to the ore pulp to be concentrated, and subjecting the same to a flotation operation.

8. The method of concentrating ores by remaining soluble extract together with the action of selective agents which comsome of the precipitated insoluble constiprises subjecting a resin to extraction with .tuents'to the ore pulp t be concentrated, 14

an alkali, precipitating insoluble constituand'subjecting the same to a flotation opera- 5 ents from the solution by means of acid and tion.

thereby obtaining a precipitate of a finely In testimony where-h] am: my signature. divided and flocculent character, adding the ALFRF. l) fiCl IWARZ. 

